What does the cryptic crossword clue "This joint let's you go, if you get it? (3,5)" mean?

The definition is "This joint let's you go, if you get it?". The wordplay uses a cryptic definition. Cryptic definition The answer is THEELBOW.

This joint let's you go, if you get it? (3,5)

Guardian Cryptic #29138 | 7 Down | 2023-08-02 flower